进出口贵金属粉末中贵金属元素的直接测定

本文研究了贵金属含量较高的贵金属粉末中的贵金属元素的直接快速测定方法，研究了试样分解方法、测定介质的影响、元素间的光谱干扰。拟定了最佳工作条件，对进出口实际样品进行了分析，其结果与原子吸收光谱及光度法的测试结果一致性较好。     

惰性气体熔融-红外吸收/热导法测定AlSi10Mg中氧氮含量北大核心

AlSi10Mg中氧氮元素的含量对材料的组织和性能具有显著影响，需对其进行准确测定。借助氧氮分析仪，采用惰性气体熔融-红外吸收/热导法建立了测定AlSi10Mg中氧氮元素含量的分析方法，对影响测定的各项参数（如助熔剂、分析功率、样品重量等）做了条件试验并予以优化。试验结果表明，本方法稳定性好，准确度高，可满足AlSi10Mg中氧氮元素的定量测试需求。     

ICP发射光谱仪测定Mg—Mn—Ce合金中各元素的含量

采用ICP-AES法直接测定Mg-Mn-Ce合金中各元素.对ICP-AES分析方法及影响因素进行研究,确定样品的溶解条件、仪器最佳工作参数和分析线,回收率在95%～105%之间,相对标准偏差小于3%.此方法准确、快速,实现了对Mg-Mn-Ce合金中各元素的同时测定.     

ICP-OES法测定氮化硅粉中微量元素Fe、Al、Ca的含量

本文提出了电感耦合等离子体发射光谱法直接测定Si3N4粉中微量元素Fe、Al、Ca含量的分析方法。进行了样品分解试验,考察了基体对测定元素的影响以及各元素间的相互干扰情况,优化了分析条件,各元素的相对标准偏差均在5%以下,回收率为94%～102%。     

光谱分析法测定硼元素方法初探

介绍了光谱分析法的基本原理和具体应用条件，并对痕量元素硼进行了分析测定，结果表明，利用光谱分析法改善了硼元素的蒸发行为，获得了较好的准确度和灵敏度。     

酸溶法测定氢氧化铝中的氧化镁

研究了用空气-乙炔火焰原子吸收法测定氢氧化铝中的镁。对测定条件、酸度的影响,共存元素干扰的加入量进行实验 结果表明Al2O3对镁测定有一定的影响。     

电感耦合等离子体发射光谱法测定铁合金中非主量元素

介绍了电感耦合等离子体发射光谱法测定铁合金中非主量元素的试验条件、测定范围、测定步骤和试验结果。经比较，本法的测定准确度、精度完全符合国家化学分析标准，也和湿化学分析方法的测定结果一致。     

原子吸收光谱法测定高氯酸锂中的钠钾

通过对介质、基体干扰、碱金属间的相互影响、电离干扰及共存元素影响的试验，选择比较理想的条件和方法来测定高氯酸锂中钠和钾。     

稀土铈对于碱性电镀锌层耐蚀性的影响

研究了稀土元素铈在碱性镀锌中的应用。试验研究了不同工艺条件的含铈镀层，优化了工艺条件；检测了当镀液中含有铈元素时，镀层耐蚀性的变化情况；利用电子探针及X射线衍射分析了含铈的试样，测定了铈进入镀层的含量，剖析了铈存在的作用及其对镀层的耐蚀性影响的原因。     

多元素铸铁成分检测方法

采用等离子体发射光谱法,通过对仪器工作条件的优化、分析谱线的选择、样品的前处理以及各元素积分区间优化后的数据再处理,解决了标准样品稀缺、多元素之间的测定干扰问题,测定了灰口样品中硅、锰、磷等21个元素。各元素标准曲线的线性均大于0.999,表明本方法可行;回收率说明该方法具有较高的分析精度。     

The effects of reactive element additions and sulfur removal on the adherence of alumina to Ni- and Fe-base alloys

The effects of reactive element additions to alumina-forming alloys (single-crystal Ni-base and ferritic Fe-Cr-Al alloys) and the effect of hydrogen annealing to remove sulfur on the oxide adherence to these alloys have been studied. The results have shown that desulfurization by hydrogen annealing can result in improvements in cyclic oxidation comparable to that achieved by doping with reactive elements. The results have also shown that there is less stress generation during the cyclic oxidation of Y-doped FeCrAl compared to Ti-doped or desulfurized FeCrAl. This indicates that the growth mechanism, as well as the strength of the oxide/alloy interface, influences the ultimate oxidation morphology and stress state which will certainly affect the length of time the alumina remains protective. It has been shown to be possible to estimate the amount of sulfur available to segregate to the alloy/oxide interface and how this is influenced by reactive element additions or hydrogen annealing. If these calculations can be made more quantitative it should be possible to engineer alumina-forming alloys for optimum resistance to cyclic oxidation e.g. by combining an appropriate desulfurization treatment and choice of reactive element addition.     

氧化还原滴定法测定铂铱合金中的铱

研究了铂铱合金中测定铱的氧化还原滴定法.对氧化条件、氯水用量、通气流量、时间及Pd、Rh、Ru等共存元素的影响进行了实验,拟定了分析方法.对合成试样及合金样品进行了测定,当铱含量为25.0%时标准偏差为0.044%.     

Compositional effects on the Type I hot corrosion of β-NiAl alloys

Cast alloys of nominal compositions Ni-36Al, Ni-36Al-5Co, Ni-36Al-5Pt, Ni-36Al-5Co-5Pt, and Ni-36Al-5Cr (at.%) were tested under Type I (900 °C) hot corrosion conditions in order to determine the influence of various elements commonly found in diffusion aluminide coatings on the resistance to this mode of attack. Chromium was found to be the most effective element in conferring hot corrosion resistance, but improvements in performance were also found with the addition of Co and/or Pt. Experimental evidence is presented which suggests that each of these elements increase the hot corrosion resistance of β-NiAl alloys primarily by increasing their ability to rapidly form a thermally grown Al₂O₃ scale and to heal this scale in the event of damage. Potential explanations for this enhanced scale formation and healing capability are discussed.     

Modeling of diffusion processes during carburization of alloys

A Model was developed for the finite-difference calculation of carburization profiles in high-temperature alloys. The method includes the ternary crossdiffusion effect due to substitutional alloying elements that are preferentially oxidized. It can be used to treat cases such as carburization of preoxidized alloys or simultaneous oxidation and carburization. Up to three distinct types of carbide precipitation reactions can be included in the calculations. The solubility product is computed for each reaction and the amount of C that reacts is removed from the diffusion process. The model can treat two sets of boundary conditions corresponding to the presence or absence of a protective oxide scale. For comparison, under protective conditions carburization profiles were obtained for preoxidized alloys using C¹⁴ radioactive tracer. The application of the model yields values for the diffusivities of C in the alloys tested. Under nonprotective conditions, the predictions of the model were compared to carburization profiles reported for pack carburization tests. The method is able to predict maximum carbide levels and penetration depths for different alloys in various conditions and can be used in the selection and design of high-temperature alloys for use in carburizing environments.     

Relative effects of enthalpy and entropy on the phase stability of equiatomic high-entropy alloys

High configurational entropies have been hypothesized to stabilize solid solutions in equiatomic, multi-element alloys which have attracted much attention recently as “high-entropy” alloys with potentially interesting properties. To evaluate the usefulness of configurational entropy as a predictor of single-phase (solid solution) stability, we prepared five new equiatomic, quinary alloys by replacing individual elements one at a time in a CoCrFeMnNi alloy that was previously shown to be single-phase [1]. An implicit assumption here is that, if any one element is replaced by another, while keeping the total number of elements constant, the configurational entropy of the alloy is unchanged; therefore, the new alloys should also be single-phase. Additionally, the substitute elements that we chose, Ti for Co, Mo or V for Cr, V for Fe, and Cu for Ni, had the same room temperature crystal structure and comparable size/electronegativity as the elements being replaced to maximize solid solubility consistent with the Hume–Rothery rules. For comparison, the base CoCrFeMnNi alloy was also prepared. After three-day anneals at elevated temperatures, multiple phases were observed in all but the base CoCrFeMnNi alloy, suggesting that, by itself, configurational entropy is generally not able to override the competing driving forces that also govern phase stability. Thermodynamic analyses were carried out for each of the constituent binaries in the investigated alloys (Co–Cr, Fe–Ni, Mo–Mn, etc.). Our experimental results combined with the thermodynamic analyses suggest that, in general, enthalpy and non-configurational entropy have greater influences on phase stability in equiatomic, multi-component alloys. Only when the alloy microstructure is a single-phase, approximately ideal solid solution does the contribution of configurational entropy to the total Gibbs free energy become dominant. Thus, high configurational entropy provides a way to rationalize, after the fact, why a solid solution forms (if it forms), but it is not a useful a priori predictor of which of the so-called high-entropy alloys will form thermodynamically stable single-phase solid solutions.     

高温钎焊过程中Ni-Cr合金对金刚石磨粒静压强度的影响

采用C类(Ni82Cr7Si4.5B3.1Fe3)和E类(BNi76Cr15P9)两种钎料对金刚石进行真空炉中钎焊。通过静压强度测试对各种状态下的金刚石钎焊性能进行评价,并借助SEM以及拉曼光谱仪对金刚石表面碳化物的形貌和金刚石的石墨化进行检测分析。结果表明:钎焊高温对金刚石强度的影响较合金钎料的化学侵蚀作用而言小很多;触媒元素Ni、Fe和强碳化物形成元素Cr等引起的化学侵蚀,是导致金刚石静压强度降低的两个主要原因;不同品质的金刚石经过高温钎焊后,静压强度值出现不同程度的降低。     

Effects of tensile twinning on the stretch formability of Mg

This study examined the influences of twinning during the Erichsen test. {10-12} tensile twinning plays the critical role in Mg alloys. Alloy elements and grain size are important factors that determine the formation of {10-12} tensile twins at room temperature. Mg-6.0Zn(Z6) and Mg-6.0Zn-0.3Ca(ZX60) alloys were fabricated and their grain size was varied under different annealing conditions. Tensile twinning is promoted by the addition of Ca, as assessed from measurements of the microstructure and the viscoplastic self-consistent calculations. The coarse-grain Ca-containing alloy showed the largest amount of tensile twinning. However, the stretch formability increased with grain size up to a certain point and then decreased. It can be inferred that microstructures with large grains activated the tensile twin, which became origins of cracks. The results of the small Erichsen test showed that tensile twinning contributes to high stretch formability releasing the stress concentration in the grain boundaries but the interaction between twin and slip causes cracks as the grain size increases.     

稀土在铝合金表面处理中的应用及研究进展

评述了稀土在铝合金表面处理中的应用及研究进展,尤其是铝合金稀土表面转化膜技术和稀土对铝合金阳极氧化的影响两方面.稀土表面转化膜能够提高铝合金的耐蚀性能,工艺以化学浸泡为主;稀土对铝合金阳极氧化是有益的:它使铝合金接受极化的能力增强,同时提高氧化膜的抗蚀性.因此,稀土应用于铝合金表面处理具有良好的发展前景.     

国产锆合金板料冲裁间隙的有限元分析

锆合金常用于制作核电设备的重要元器件。为了提高国产锆合金板料冲裁的产品质量与模具寿命,针对锆合金板料价格昂贵和各向异性明显的特点,利用有限元模拟软件研究不同冲裁间隙下的冲裁效果。通过试验测得国产锆合金的材料参数,利用有限元软件模拟分析在冲裁过程中冲裁力、冲裁功和工件断面质量随冲裁间隙变化的趋势;研究合理冲裁间隙的取值、以及厚向异性系数对合理冲裁间隙和断面质量的影响;通过裂纹扩展方向分析和实物断面分析验证了模拟分析的正确性。结果表明,厚度为0.47 mm锆合金板料的合理冲裁间隙为0.035 mm;厚向异性系数的变化对合理冲裁间隙的取值没有明显影响,但是对工件断面质量有显著影响。     

两种Ti—Al金属间化合物基合金ISM熔炼过程中Al元素挥发控 …

对水冷铜坩埚真空感应熔炼过程中合金元素的挥发动力学进行了深入的分析,并在此基础上建立了ＩＳＭ熔炼过程中Ａｌ元素挥发控制方式的判断模型。对Ｔｉ－４８Ａｌ－２Ｃｒ－２Ｎｂ（ａｔ％）和Ｔｉ－２４Ａｌ－１１Ｎｂ（ａｔ％）合金中Ａｌ元素挥发控制方式的判断结果表明：随着熔体温度的升高和外压的增大,Ａｌ元素的挥发由低温和高压时的界面挥发控制向高温和低压时的界面挥发和液相中扩散同时起作用的双重控制方式转变,只是对